The present invention relates to a modeling method and a simulation method. More to particularly this invention relates to a modeling method for forming a simulation model when analyzing power/ground noise of circuit board, and/or its small area by circuit simulator and to a simulation method for using the simulation model formed.
With speed up of the computer, power/ground noise occurring in LSI (Large Scaled Integration) package and/or printed circuit board is actualized as hindrance main cause of speed up or as occurrence main cause of EMI (Electromagnetic Interference). Settlement of a more accurate simulation method is desired for reducing power/ground noise.
The power/ground noise xcex94V is determined by the product of current change quantity xcex94i and impedance Z. The current change quantity xcex94i occurs caused by switching of current change source mainly. Further, the impedance Z is impedance between power layer into which the current change quantity xcex94i flows and the ground layer, thus the impedance Z is determined according to structure of LSI package and/or printed circuit board.
To diminish both of the current change quantity xcex94i and the impedance Z is effective for reducing power/ground noise. So, to grasp accurately the current change quantity xcex94i and the impedance Z is necessary for reducing power/ground noise.
For instance, in circuit simulation using SPICE (Simulation Program with Integrated Circuit Emphasis) simulator, it was necessary to describe (modeling) physical structure such as LSI package and/or printed circuit board with electrical element such as transistor model, inductance, capacitance, and resistance whose input form is capable of being understood by the simulator. In particular, in order to improve the precision of the simulation of power layer/ground layer, it was necessary to describe them with the electrical element as small matrix shape. (For instance, referring to Jong-Gwan Yook et al. xe2x80x9cComputation of Switching Noise in Printed Circuit Boardsxe2x80x9d, IEEE TRANSACTIONS ON COMPONENTS, PACKAGING, AND MANUFACTURING TECHNOLOGY-PART A, VOL. 20, NO. 1, MARCH 1997).
The first problem is that the modeling of the matrix shape improves precision of the simulation, while the modeling of the matrix shape brings increase of execution time of the simulation. Specially, in the modeling regarding the LSI package using general purpose modeler and/or printed circuit board, in order to balance the simulation precision with the simulation execution time, it is necessary to optimize physical form to be inputted to the modeler artificially corresponding to frequency wanted to analyze, thus considerable knowledge and know-how are necessary.
In view of the foregoing, it is an object of the present invention in order to overcome the above-mentioned problems, to provide a modeling method capable of forming model without describing circuit board and/or small area of circuit board using matrix shape and without deteriorating simulation precision.
It is another object of the present invention to provide a simulation method, applying above modeling method, capable of realizing simulation of power/ground noise while balancing simulation precision with simulation executing time.
It is still another object of the present invention to provide storage medium storing therein a program for executing above modeling method and/or the simulation method.
According to a first aspect of the present invention, in order to achieve the above mentioned objects, there is provided a modeling method in which a simulation model of a circuit board with one current change source is formed when analyzing power/ground noise of the circuit board by a circuit simulator, comprising the processes of regarding the circuit board as an aggregate of doughnut boards having a form of thin concentric circle with the current change source as the center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, and connecting said transmission line models in series to make said simulation model of the circuit board.
According to a second aspect of the present invention, there is provided a modeling method in which a simulation model of a small area of circuit board having a current change source at a center is formed when analyzing power/ground noise of the small area of circuit board by a circuit simulator, comprising the processes of regarding the small area of circuit board as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in said aggregate of rectangular boards while each rectangular board is a transmission line, and connecting the transmission line models in series to make the simulation model of said small area of circuit board.
According to a third aspect of the present invention, there is provided a simulating method in which a simulation model of a circuit board with one current change source is formed, and a simulation of power/ground noise of the circuit board is executed by a circuit simulator, comprising the processes of regarding the circuit board as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make the simulation model of the circuit board, connecting the current change source to a board center end of the simulation model of the circuit board, connecting an ideal power to a board periphery end of the simulation model of the circuit board, and observing connecting points of the transmission line models while changing the current of the current change source.
According to a fourth aspect of the present invention, there is provided a simulating method in which a simulation model of a circuit board with one current change source is formed, and a simulation of power/ground noise of the circuit board is executed by a circuit simulator, comprising the processes of regarding the circuit board as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make the simulation model of the circuit board, connecting the current change source to a board center end of the simulation model of the circuit board, connecting an ideal power to a board periphery end of the simulation model of the circuit board, connecting a de-coupling capacitor model to a periphery of the current change source, and observing connecting points of the transmission line models while changing the current of the current change source.
According to a fifth aspect of the present invention, there is provided a simulating method in which a simulation model of a small area of circuit board having a current change source at a center is formed, and a simulation of power/ground noise of the small area of circuit board is executed by a circuit simulator, comprising the processes of regarding the small area of circuit board as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumference of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make the simulation model of the small area of circuit board connecting the current change source to a region center end of the simulation model of the small area of circuit board, connecting an ideal power to a region periphery end of the simulation model of the small area of circuit board, and observing connecting points of the transmission line models while changing the current of the current change source.
According to a sixth aspect of the present invention, there is provided a simulating method in which a simulation model of a small area of circuit board having a current change source at a center is formed, and a simulation of power/ground noise of the small area of circuit board is executed by a circuit simulator, comprising the processes of regarding the small area of circuit board as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make the simulation model of the small area of circuit board, connecting the current change source to a region center end of the simulation model of the small area of circuit board connecting an ideal power to a region periphery end of the simulation model of the small area of circuit board connecting a de-coupling capacitor model to a periphery of the current change source, and observing connecting points of the transmission line models while changing the current of the current change source.
According to a seventh aspect of the present invention, there is provided a storage medium storing therein a computer implemented program, the computer implemented program implementing the processes of regarding a circuit board with one current change source as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, and connecting the transmission line models in series to make a simulation model of the circuit board.
According to an eighth aspect of the present invention, there is provided a storage medium storing therein a computer implemented program, the computer implemented program implementing the processes of regarding a small area of circuit board having a current change source at a center as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, and connecting the transmission line models in series to make a simulation model of the small area of circuit board.
According to a ninth aspect of the present invention, there is provided a storage medium storing therein a computer implemented program, the computer implemented program implementing the processes of regarding a circuit board with one current change source as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lengths of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make a simulation model of the circuit board connecting the current change source to a board center end of the simulation model of the circuit board, connecting an ideal power to a board periphery end of the simulation model of the circuit board, and observing connecting points of the transmission line models while changing the current of the current change source.
According to a tenth aspect of the present invention, there is provided a storage medium storing therein a computer implemented program, the computer implemented program implementing the processes of regarding a circuit board with one current change source as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lenghts of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make a simulation model of the circuit board, connecting the current change source to a board center end of the simulation model of the circuit board, connecting an ideal power to a board periphery end of the simulation model of the circuit board, connecting a de-coupling capacitor model to a periphery of the current change source, and observing connecting points of the transmission line models while changing the current of the current change source.
According to an eleventh aspect of the present invention, there is provided a storage medium storing a computer implemented program, the computer implemented program implementing the processes of regarding a small area of circuit board having a current change source at a center as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lenghts of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make a simulation model of the small area of circuit board, connecting the current change source to a region center end of the simulation model of the small area of circuit board, connecting an ideal power to a region periphery end of the simulation model of the small area of circuit board, and observing connecting points of the transmission line models while changing the current of the current change source.
According to a twelfth aspect of the present invention, there is provided a storage medium storing a computer implemented program, the computer implemented program implementing the processes of regarding a small area of circuit board having a current change source at a center as an aggregate of doughnut boards having a form of thin concentric circles with the current change source as a center, approximating the aggregate of doughnut boards to an aggregate of rectangular boards with respective circumferences of the doughnut boards as widths and respective cut-lenghts of the same as lengths, forming a transmission line model for each rectangular board in the aggregate of rectangular boards while each rectangular board is a transmission line, connecting the transmission line models in series to make a simulation model of the small area of circuit board, connecting the current change source to a region center end of the simulation model of the small area of circuit board, connecting an ideal power to a region periphery end of the simulation model of the small area of circuit board, connecting a de-coupling capacitor model to a periphery of the current change source, and observing connecting points of the transmission line models while changing the current of the current change source.
The above and further objects and novel features of the invention will be more fully understood from the following detailed description when the same is read in connection with the accompanying drawings. It should be expressly understood, however, that the drawings are for purpose illustration only and are not intended as a definition of the limits of the invention.